On a collaborative project, with Dr. P.V. Subba Pao at the Indian Institute of Science, we have isolated and characterized three antigens from shrimp. These three substances appear to account for the majority of allergenic material. Two are glycoproteins, and a third is tRNA. The characterization of these antigens leads the way to the production of improved diagnostic and therapeutic reagents for the management of shrimp sensitivity. Six normal subjects and twelve patients with suspected sensitivity to aspartame have participated in a NIAID-CRS approved blinded challenge protocol. One individual with a history of adverse reactions developed several hives during single- but not double- blind challenge. Plasma histamine levels remained normal in all cases. Two normal subjects, three asthmatics, and one individual with a history of hives from MSG have participated in a NIAID-CRS approved protocol for MSG sensitivity. No adverse responses were noted to MSG, and no changes occurred in plasma histamine levels. Measurable amounts of histamine were found within a number of foods. The amount of histamine appears to be insufficient to induce a clinical response by itself alone, but suggests the possibility that histamine may potentiate reactions to other substances within foods.